This invention relates in general to microvalves of the general type described and illustrated in U.S. Pat. Nos. 7,210,502, 7,803,281, 8,011,388, 8,113,482, and 8,156,962 and in U.S. Published Patent Application Nos. 2007/0172362, 2007/0251586, 2008/0042084, 2009/0123300, 2010/0012195, 2010/0084031, 2011/0127455, 2012/0000550, 2012/0145252, 2012/0140416, 2012/0295371, and 2012/0299129. The disclosures of all of these patents and patent applications are incorporated herein by reference. In particular, this invention relates to a valve assembly including such a microvalve that is used as a first stage to control the operation of a second stage valve for regulating the flow of an isolated fluid therethrough.
MEMS (micro electro mechanical systems) are a class of systems that are physically small, having some features or clearances with sizes in the micrometer range or smaller (i.e., smaller than about 10 microns). These systems have both electrical and mechanical components. The term “micro machining” is commonly understood to mean the production of three-dimensional structures and moving parts of MEMS devices. MEMS originally used modified integrated circuit (e.g., computer chip) fabrication techniques (such as chemical etching) and materials (such as silicon semiconductor material) to micro machine these very small mechanical devices. Today there are many more micro machining techniques and materials available.
The term “MEMS device” as may be used in this application means a device that includes a micro machined component having some features or clearances with sizes in the micrometer range, or smaller (i.e., smaller than about 10 microns). It should be noted that if components other than the micro machined component are included in the MEMS device, these other components may be micro machined components or standard sized (i.e., larger) components.
Similarly, the term “microvalve” as may be used in this application means a valve having features or clearances with sizes in the micrometer range, or smaller (i.e., smaller than about 10 microns) and thus by definition is at least partially formed by micro machining. The term “microvalve device” as may be used herein means a device that includes a microvalve, and that may include other components. It should be noted that if components other than a microvalve are included in the microvalve device, these other components may be micro machined components or standard sized (i.e., larger) components.
The term “MEMS package” as used herein should be understood to mean a device, which includes a micromachined component and may include other components that may be micromachined components or standard sized components. A “MEMS fluidic package” should be understood to be a MEMS package including a fluid passageway. A “MEMS electrofluidic package” as used herein should be understood to be a MEMS package including a fluid passageway and an electrically active component that may be a micromachined component. A “MEMS package platform” as used herein should be understood to be an interface component or assembly of components upon which a MEMS device may be mounted and by means of which the MEMS device can be interfaced with an external system.
Microvalves of this general type have been successfully used to control the flow of various fluids therethrough. However, it has been found difficult to use microvalves of this general type to control the flow of certain other fluids therethrough. Thus, it would be desirable to provide an improved structure for such a microvalve that is used as a first stage to control the operation of a second stage valve for regulating the flow of an isolated fluid therethrough.